This invention relates to swash-plate type compressors which are adapted for use in air conditioning systems for automotive vehicles or the like, and more particularly to a compressor of such type which has a lubricating oil reservoir having an increased volume.
A conventional swash-plate type compressor generally used in air conditioning systems for automotive vehicles and the like systems comprises a cylinder block formed of at least one piece, a drive shaft extending through the cylinder block along its axis and rotatable relative to the cylinder block, and a swash plate secured on the drive shaft. The cylinder block has three cylinder bores which each have a piston slidably received therein and which axially extend through the cylinder block in an arrangement circumferentially spaced from each other, three spaces opening in each end face of the cylinder block and each arranged between adjacent ones of the cylinder bores, and a swash plate chamber formed at a central portion of the cylinder block. The pistons received within the cylinder bores are arranged in engagement with the swash plate arranged within the swash plate chamber and are reciprocatingly moved within the cylinder bores by the rotation of the swash plate which is caused by the rotation of the drive shaft, to carry out compression actions. The compressor is so disposed that the three cylinder bores are in an array of equilateral triangle with the diametric center of each cylinder bore taken as each vertex of the equilateral triangle, while the three spaces are in an array of inverted triangle with the diametric center of each space taken as each vertex of the inverted triangle. The lower one of the three spaces in the array of inverted triangle and a lower portion of the swash plate chamber form an oil reservoir in which lubricating oil is stored.
The lubricating oil stored in the oil reservoir is splashed upwardly by the swash plate during its rotation into oily mist, which is partly supplied to the portions of engagement of the swash plate with the pistons to lubricate same, and partly led into lower pressure chambers (suction chambers) communicating with the cylinder bores due to a difference in pressure between the swash plate chamber and the lower pressure chambers which is produced by the reciprocating motions of the pistons, the oil which is led into the lower pressure chambers, lubricating radial bearings supporting the drive shaft at locations between the swash plate chamber and the lower pressure chambers. The lubricating oil thus led into the lower pressure chambers are sucked into the cylinder bores together with compression medium and leaked into the refrigerating circuit outside the compressor. When the amount of lubricating oil thus leaked is large or the amount of lubricating oil which is returned from the refrigerating circuit to the compressor is small, the amount of lubricating oil which is stored in the oil reservoir within the compressor becomes insufficient, providing the possibility of seizure of the portions of engagement of the swash plate with the pistons or other portions of the compressor.
Particularly in the conventional compressor of the above arrangement, the oil reservoir which is formed of part of the swash plate chamber and only one of the three spaces has a limited oil storing volume. Therefore, the possibility of seizure of the above-mentioned portions is very large.